1. Field of the Invention
Aspects of the present invention relate to a method of forming a polycrystalline silicon layer and an atomic layer deposition apparatus used for the same, and more particularly, to a method of forming a polycrystalline silicon layer and an atomic layer deposition apparatus in which a crystallization-inducing metal may be deposited on an amorphous silicon layer at a predetermined position and a uniform concentration by modifying a predetermined region of a surface of the amorphous silicon layer into a hydrophilic surface or a hydrophobic surface. Thus, seed position and grain size may be controlled.
2. Description of the Related Art
Generally, polycrystalline silicon layers are widely used as semiconductor layers for thin film transistors since the polycrystalline silicon layers have high field effect mobility, and enable application to high-speed operating circuits and formation of CMOS circuits. Thin film transistors using the polycrystalline silicon layers are mainly used for active devices of active-matrix liquid crystal display (AMLCD) devices, and switching and driving devices of organic light emitting diode (OLED) display devices.
Examples of methods of crystallizing amorphous silicon into polycrystalline silicon include solid phase crystallization (SPC), excimer laser crystallization (ELC), metal-induced crystallization (MIC) and metal-induced lateral crystallization (MILC) methods. In the SPC method, an amorphous silicon layer is annealed for several to several tens of hours at a temperature of about 700° C. or less, which is the thermal deformation temperature of glass forming a substrate of a display device using a thin film transistor. In the ELC method, an excimer laser is applied to an amorphous silicon layer to locally heat the amorphous silicon layer for a very short period of time at high temperature. In the MIC method, a crystallization-inducing metal such as nickel, palladium, gold or aluminum is in contact with or injected into an amorphous silicon layer to induce a phase change into a polycrystalline silicon layer, and in the MILC method, a silicide produced by reacting a crystallization-inducing metal with silicon then laterally propagates, sequentially inducing crystallization of the amorphous silicon layer. However, the SPC method requires a long processing time, and easily causes deformation of a substrate due to long annealing at high temperature, and the ELC method requires high-priced laser equipment and has poor interface characteristics between the polycrystallized silicon semiconductor layer and a gate insulating layer due to protrusions occurring on the polycrystallized surface.
Today, research into methods of crystallizing an amorphous silicon layer using a crystallization-inducing metal has been widely conducted because of faster crystallization at a lower temperature than the SPC method. Examples of these crystallization methods using a crystallization-inducing metal include MIC, MILC, and super grain silicon (SGS) crystallization methods.
In the crystallization methods using a crystallization-inducing metal, the crystallization-inducing metal is deposited on an amorphous silicon layer by sputtering, ion implantation or thermal evaporation. However, in these methods, metal particles to be deposited randomly propagate from a metal target, and thus there is a limit in being able to uniformly deposit a metal catalyst to have a concentration as high as 1011 to 1016 atoms/cm2. Recently, while a technique of uniformly depositing crystallization-inducing metals on an amorphous silicon layer using micro-electro-mechanical systems (MEMS) technology has been disclosed, this has disadvantages of length of preparation time in mass-production, which may not be suitable for commercialization.